1. Field of the Invention
The invention relates to television electronic programming guides (“EPGs”). More particularly, it relates to a method and apparatus for cost-effective memory management.
2. Description of the Related Art
Prior art EPGs provide television viewers with on-screen television schedule information presented, e.g., in a convenient, regular or non-regular rectangular grid format. One type of EPG is used in conjunction with an analog television system. That type of EPG sometimes is called a passive programming guide (“PPG”). In such a system, one of the cable channels is reserved for displaying programming information. The programming information is displayed in a grid pattern. The first column lists the various channels of the cable broadcast system. Additional columns, e.g., columns two, three and four, display program information for what is showing on the channels listed in the first column, in half-hour increments. For example, suppose that a person tunes to an EPG at 10:35 p.m., the second column would display program information for 10:00–10:30 p.m., the third column would display program information for 10:30–11:00 p.m., and the fourth column would display program information for 11:00 p.m. 11:30 p.m. A row at mid-screen displays the time slots relating to the second, third and fourth columns. A portion of the television (“TV”) screen typically provides continuous advertisements.
Cable TV systems typically provide more television channels than there is space for rows in a useable grid pattern. A grid is typically used that scrolls at a pre-selected slow rate, so that a viewer can see what is showing on all of the channels. In the case of satellite broadcasts, the situation becomes even more complex. Digital satellite TV systems may provide 1,000 TV channels with various TV programs and services.
The program schedule information contained in an analog EPG is typically broadcast by an operator on a dedicated one of the channels of the cable TV system. However, most digital EPGs operate in a different way. In a digital EPG, program schedule information and sometimes applications and/or systems software is transmitted to equipment located on the viewer's premises (e.g., a digital set-top box) by way of broadcast, cable, direct satellite or other suitable form of transmission. A digital set-top box (“STB”) serves to deliver compressed digital video, data and audio signals in real time usable form to one or more TV sets. The STB, which is basically a dedicated computing device, contains memory allowing the program schedule information to be stored for later viewing. The program schedule information stored in the STB is periodically updated, e.g., on a continuous, daily, weekly, or biweekly basis or any other useful pattern. A microprocessor within the STB utilizes the viewer's TV set to display the stored program schedule information and to implement other functions of the EPG in response to user-generated signals. The functions available to the viewer vary depending on the sophistication of the particular EPG and hardware capabilities.
Digital EPGs are often used in an interactive television system and are sometimes called interactive programming guides (“IPGs”). In an interactive television system EPG, a user may browse schedule information in any order, select programs from on-screen menus for current or future viewing, and order pay-per-view programming on demand. Some (advanced) EPGs permit other functions, e.g., an e-mail function, or a function that permits a user to block certain kinds of programs, such as adult or violent programs, and choose favorite channels. Prior art digital EPGs, however, collectively fail to provide viewing capabilities that realistically address the viewing habits of the users of these systems.
As mentioned above, an analog TV EPG is viewed on a TV screen as a continuously scrolling rectangular table. This solution does not allow any user interaction and is suitable only for the passive television viewer. This is a poor solution for interactive TV, because:    1. The scrolling speed is set upfront (it is not necessarily constant) and cannot be adjusted by user's request.    2. In an analog EPG system, the user cannot switch to the channel of choice immediately from the EPG (e.g., by clicking on a display of a channel number on the EPG). Instead, the user must input the channel number with a remote controller.    3. The analog EPG scrolling table is completely sequential (providing information in an order depending upon channel number and designer's chosen style) and the user cannot pre-sort schedule data or otherwise personalize the EPG.
A more sophisticated solution is the interactive EPG or (“IPG”). Unfortunately existing solutions have their own problems. For example, interactive EPG systems provide drop-down menus that require multiple steps in order to interact with the EPG, which can lead to user frustration when a search for a desired program is unsuccessful or simply too complicated. As known today, interactive EPGs are inflexible in terms of menu design, because the menu itself is a set of regular two-dimensional grids.
Additional problems with the prior art electronic programming guides are listed below.    1. Program Description Truncation. When displaying schedule information in grid format, i.e., columns representing time slots and rows representing channels, program titles are generally truncated to fit into the cells of the grid. The width of a grid cell varies with the program duration. Since a 30-minute program is allotted only a small space for the program title and description, titles and/or descriptions for half- and even full-hour programs often must be truncated to fit in the allotted space. Some systems simply cut off the description of a program without abbreviating it in any way, such that the user cannot determine the subject matter of the program. While some systems partially alleviate this problem by providing two lines of text in each grid cell, this is a less than ideal solution because program descriptions may still be truncated.    2. Inability to Create a Program Itinerary While Viewing a TV Program. Prior art EPGs lack a method for a user to create a program itinerary, electronically, concurrently while the user views a program on the TV screen. Thus, when a user views a program on a particular channel, he or she cannot electronically set up a sequence of other channels to surf.    3. Inability to Simultaneously Channel Surf and View EPG. Prior EPGs leave much guess work for the user as he or she navigates through a sequence of channels. When skimming through channels and trying to determine what program is being displayed on a channel, commonly known as “channel surfing,” the user must guess which program is currently being aired from the video segment encountered during channel surfing. Since up to thirty percent of the programming appearing on a channel at any given time is advertising, the user is not provided with any clues as to what program is showing on a selected channel at a given time. Hence, the user often has no choice but to wait until an advertisement or commercial ends before learning what program is showing on the selected channel. Existing solutions allow user to go to the channel and find more information by using a special button of remote control, i.e., “info” button. Thus, a need exists for an EPG that displays current program schedule information for each channel at the same time that the user surfs through the channels.    4. Text Size. Unfortunately, existing EPGs allow for only one font size. However, human beings do not all have the same acuity of vision. As a result, two problems appear: some viewers may have difficulty or even be unable to read the information in the EPG and some viewers want to see more information using smaller font.    5. Specular Highlighting. Existing EPGs provide only a very rudimentary lighting capability. For example, existing EPGs do not have an adequate means to adjust the brightness of the EPG. This detracts from the utility of the EPG.
Thus, methods and apparatus for generating a two-dimensional (“2D”) TV graphical user interface (“GUI”) for providing TV program guides on a TV screen are known in the art. A conventional TV GUI uses a single layer of on-screen display graphics to present TV program information and, typically, multiple menus are provided to enable users to navigate through the presented information. For example, an apparatus that generates a main menu of a program guide, which includes program source information and program event information for a plurality of program sources, and further generates navigation menus for allowing a viewer to modify the program guide is disclosed in U.S. Pat. No. 5,694,176, issued Dec. 2, 1997 to Bruette et al. A system and a process in which a program listing is displayed as a grid of two-dimensionally arranged adjacent irregular cells, which vary in length corresponding to time duration of the programs, with a title of a program being displayed in each of said irregular cells, said grid having a plurality of channels listed in a first dimension and time listed in a second dimension, is disclosed in U.S. Pat. No. 5,809,204, issued Sep. 15, 1998 to Young.
A multi-layered TV GUI that uses a memory for storing graphics data that is capable of storing two graphics planes that represent upper and lower layers of graphics displayable on a TV screen, and that uses a graphics accelerator to combine the graphics planes to produce various graphical effects on the screen is disclosed in U.S. Pat. No. 6,016,144, issued Jan. 18, 2000 to Blonstein et al. (hereinafter “Blonstein '144”). One advantage of a multi-layered TV GUI that produces multiple layers of graphics on a TV screen is that it eliminates the need for a multi-menu hierarchical system. (A hierarchical menu system often causes confusion when the user loses track of the menu that he or she came from and how to get back.) A variety of other TV GUI are disclosed in the following additional issued patents: U.S. Pat. No. 4,706,121, issued Nov. 10, 1987 to Young (hereinafter “Young '121”); U.S. Pat. No. 5,781,246, issued Jul. 14, 1998 to Alten et al.; U.S. Pat. No. 5,986,650, issued Nov. 16, 1999 to Ellis et al.
In Young '121, the multi-layered TV GUI provides a TV GUI that adjusts graphical presentation in a matrix of text to expose a predetermined portion of a lower layer of graphics. In Blonstein '144, electronic program schedule data is stored in a system memory and, during the rendering process, converted into a set of bit-maps (one bitmap for each single layer) and stored in a graphics accelerator buffer memory. However, while prior art EPGS, such as Young '121 and Blonstein '144 relate generally to graphical displays and in particular to navigation within a 2D graphical display space, they do not approach the advantages of a 3D graphical display.
What is clearly needed is a method and system for cost-effective optimal storing of electronic program schedule data using a combination of on-chip memory and system memory for 3D-enabled EPGs.